Presently, in wireless communication field, demand of handheld electronic products dramatically increases day by day, and the handheld electronic products are developed according to trends of compactness. Most of traditional handheld electronic products can receive different electro-magnetic signals in two or more communication frequency bands. For allowing a handheld electronic product to receive electro-magnetic signals in a plurality of frequency bands, an internal antenna installed in the handheld electronic product is generally designed to have a considerable size and a plurality of radiation portions for receiving different frequency bands, in order to ensure that the handheld electronic product has a better receiving effect.
However, if it needs the internal antenna to receive electro-magnetic signals well in at least two frequency bands, the size of the antenna must be designed to be a considerable size. The development trend of compactness inevitably limits usable internal space in the handheld electronic product for receiving the internal antenna. Thus, the limited space in the handheld electronic product for receiving the internal antenna can not satisfy the need of providing a sufficient space for installing the internal antenna with the considerable size. If the handheld electronic product is designed to narrow the antenna receiving space to satisfy the compactness trend of the handheld electronic product, the receiving effect of the handheld electronic product will be inevitably lowered, and even can not normally work during communication.